Syngas production through H2O/CO2 thermochemical splitting

CO2 and H2O can be energy-upgraded through solar thermochemical cycles. Suitable redox materials are reduced in a solar reactor at high temperature (above 1300-1400°C) and afterwards re-oxidised by CO2 and/or H2O flow, thus producing CO and/or H2. Ceria was recognised as one of the most interesting materials for this process. However, high reduction temperature, low re-oxidation kinetics as well as low stability hindered its practical application. In this work, the redox properties of Ce0.75Zr0.25O2 system prepared by hydrothermal synthesis were compared with those of a co-precipitated sample with the same nominal composition used as reference. Samples were characterised by XRD and N2 physisorption; their self-reducibility and CO2 splitting activity were tested in a thermogravimetric balance, while H2O splitting properties were studied in an ad hoc fixed bed reactor on H2 pre-reduced samples. Obtained results proved that the material prepared by hydrothermal synthesis is characterised by both improved reducibility and splitting activity.